Automatic pistol firing mechanism



Nov. 8, '1960 F. E. STURTEVANT AUTOMATIC PISTOL FIRING MECHANISM 3 Sheets-Sheet 1 Filed March 18, 1958 FIGJ INVENTOF? FOSTER El- STURTEVANT BY ATTORNEY Nov. 8, 1960 AUTOMATIC PISTOL Filed March 18, 1958 FIC5-2A F. E. STURTEVANT FIRING MECHANISM 3 Sheets-Sheet 2 Mil ATTORNEY Nov. 8, 1960 I F. E. STURTEVANT 2,959,107

' AUTOMATIC PISTOL FIRING MECHANISM Filed March 18, 1958 s Sheets-Sheet s F" |G 3A 60 )dla 44 \1 b INVENTOF? FOSTER E STLJRTEVANT ATTORNEY United States Patent 6 AUTOMATIC PISTOL FIRING MECHANISM Foster E. Sturtevant, West Hartford, Conn., assignorgby mesne assignments, to Colts Patent Fire Arms Manufacturing Company, Incorporated, Hartford, Conn., a corporation of Arizona Filed Mar. 18, 1958, Ser. No. 722,299

Claims. (Cl. 89-145) This invention relates to automatic pistols of the type herein disclosed, and more particularly has reference to pistols of this type having improved means for preventing an unintentional repetitive firing of a shot, caused by the counterrecoil of the moving parts of the pistol from the firing of a previous shot,

An automatic pistol of the type herein disclosed comprises a frame having a grip portion, a barrel connected with the frame, a slide guided on the upper portion of the frame for recoil movement relatively to the said frame and barrel, a reaction spring for opposing 'recoil movement of the slide and for returning it to its forward position after recoil, and a firing mechanism on the frame and slide.

The principal object of my invention is to provide means in the lock-work mechanism of the pistol which will insure against unintentional repetitive firing of a shot by the impact of the counterrecoil of the slide, following the firing of a previous shot.

A further object of the invention is to provide means whereby the extremely close tolerances required for cer tain coacting parts of the lock-work mechanism may be increased, and thereby obtain a greater range of interchangeability of said parts, with resulting reduction in cost of manufacture of the pistol.

With these and other objects in view which may be incident to my improvements, my invention consists in the combination and arrangement of elements hereinafter described and illustrated in the accompanying drawings in which:

Fig. 1 shows a side elevation, partly in section, of a prior art automatic pistol of the type to which my invention is applied;

Figs. 2A, B and C, show a section, on an enlarged scale, of the rear portion of the pistol of Fig. 1, to indicate the successive positions of the elements of the lock work mechanism during the firing of a shot;

Figs. 3A, B and C, are views corresponding to Figs. 2A, B and C, but showing the incorporation of the elements of my invention.

Fig. 4 is an isometric, exploded view of the lock-work mechanism, according to my invention; and

Fig. 5 is a fragmentary view, on an enlarged scale, of the contacting portions of .the sear and hammer elements of the firing mechanism.

As shown in Fig. 1, the pistol comprises a frame having a grip portion 12 with a forwardly extending upper portion 14, and a housing 15. A slide 16 is guided on the upper part of the frame for rectilinear rearward and forward movement thereon. A main reaction spring 18 biases the slide 16 toward its forward position, and a barrel 20 engages the slide 16 and is partly enclosed thereby, the barrel having the usual bore and having a cartridge chamber 21. The rear portion 22 of the slide 16 constitutes the breechblock, having a front face 23 engageable with the rear of the barrel when the slide 16 is in forward position. The breechblock also has a face 24 which is positioned to engage the rear Patented Nov. 8, 1960 face of the head of a cartridge in the chamber 21 of the barrel when the slide is in forward position.

The breechblock portion 22 of the slide carries a longitudinally movable firing pin 30 which is biased to its relatively rearward position by a spring 32. A pivoted spring-pressed hammer 34 is carried by the frame for engaging the firing pin 30 to elfect firing, the hammer as shown in Fig. 1 being in its cocked position. The hammer 34 is released by pressing a trigger 36, the hammer then moving so as to strike the firing pin 30 and thus effect firing. Upon firing, the slide 16 moves rearwardly as the result of recoil and in opposition to the reaction spring 18 and in so moving it engages the hammer 34 to restore the hammer to its cocked position. Following recoil movement, the reaction spring 18 returns the slide to its forward position.

During the recoil movement of the slide the empty cartridge shell is extracted from the chamber in the barrel and is ejected through the ejection opening 37. The extracting and ejecting means are or may be conventional and are not shown.

In Figs. 1, 2 and 3, and 4, the same elements are denoted by the same reference numerals.

Asshown in Figs. 1 and 2, the lock-work mechanism for the operation of hammer 34 by trigger 36 comprises a rearwardly extending bar 40, integral with the trigger and aligned to contact the lower end of a disconnector 42 which is pivotally mounted on a pin 44. The upper end of the disconnector 42 terminates in a cylindrical lug 46, which reciprocates in a bore 48 in the frame 10 and has a Wedge-shaped head 50 extending above the bottom edge of the slide 16. An arcuate notch 52 in slide 16 spans head 50 and is adapted to produce a downward thrust thereon when the slide 16 moves rearwardly during recoil when a shot is fired, The disconnector 42 is provided with an essentially square hole 54 (Fig. 4) which loosely surrounds pin 44 and permits downward movement of the disconnector upon application of the aforesaid thrust on head 50. The lower end of disconnector 42 is provided with a bevelled edge 56, against which bears the upper end of a spring 58 whose lower end is fastened to the grip portion 12 of frame 10, whereby the lower end of disconnector 42 is biased in an upward and forward direction. The lower end of disconnector 42 also has a pair of integral lugs 59, which extend at a right angle therefrom (Fig. 4), and are aligned to be contacted by the left end of trigger bar 40 when the trigger is moved rearwardly as shown in Figs. 2B and C.

During recoil or when the shooter manually retracts slide 16 to its rearmost position, the lower edge of the slide engages the upper face of the hammer 34 and rotates said hammer to its rearmost (cocked) position, as shown in Fig. 2.

A sear 60, which pivots on pin 44 mounted in frame 10, terminates at its upper end in a finger 62 which engages in a notch 64 in hammer 34 when the latter is in full-cocked position, as shown in Fig, 2. Hammer 34 is pivotally mounted on a pin 66 fixed in frame 10, and has an articulately connected hammer strut 68, which is pressed upward by a heavy spring (not shown) within housing 15 (Fig. 1). This upward movement of strut 68 rotates hammer 34 clockwise when the disengagement of finger 62 from notch 64 is effected by rearward pressure upon trigger 36, and the resulting rotation of the hammer causes it to strike firing pin 30 and a shot is fired.

Trigger 36 is provided with an adjustable stop 70 which contacts magazine catch 71 and thus limits the rearward movement of the trigger when a shot is fired, as clearly shown in Fig. 2C.

Figs. 2A, B and C show the relative, sequential positions of the several elements of the lock-work firing mechanism during the operation of firing a shot. In Fig. 2A, the trigger 36 is in its normal (forward) position, wherein the left end of trigger bar 40 is out of contact with lug 59 on discon'nector 42, and the latter is up and away from seat 60; also the hammer 34 is held in cocked position by theen agement of finger 62 in notch 64. In Fig. 2B, the trigger 36 has been retracted to nearly its rearmost (trigger back) position, wherein the left end of trigger bar 40 has engaged lug 59 on disconnector 42, moving its lower end rea'rwardly until the upper rear end portion of l'u'g 59 engages the lower front end portion of scar 60. Now all of the trigger slack is taken up, but the trigger stop 70 is still clear of magazine catch 71; disconnector' 42 is back touching the sear, with ing 59 touching the lower end of scar 60; and hammer 34 is held in cocked position by the engagement of finger 62 in notch 64, but is about to release the hammer. A slight further rearward movement (i.e. about .010" to .015") of trigger 36 causes finger 62 to disengage from notch 64 which releases hammer 34 to strike firing 'pin 30, whereby a shot is fired.

Fig. 2C shows the relative positions of the elements of the lock-work mechanism after a shot is fired. Here, the pistol has ejected the fired shell, is reloaded and cocked; the trigger 36 is back in its rearmost position, with stop 70 in contact with magazine catch 71; disconnector 42 is pressed downward by the rearward movement of slide 16 during recoil and held down by the engagement of lug 59 with the bottom edge of sear 60; and hammer 34 is held in cocked position by engagement of sear finger 62 in notch 64.

In the position of the elements shown in Fig. 2C, the pistol has fired and the disconnector 42 is attempting to return to its normal (Fig. 2A) position but since the re cocking action is extremely fast, the trigger 36 is still held back against magazine catch 71 by the finger of the shooter, and the disconnector can not rise, being held down by the engagement of the lug 59 with the lower front corner of sear 60. Since the sear 60 moves only .010" to .015" in releasing the hammer 34, the disconnector lug 59 is overlapping the sear 60 by only that amount. Since only a light pressure is required by the shooters finger to fire the arm, the pistol may be so severely jolted by the impact of the counter-recoiling slide 16 that the pistol is oscillated forward then backward in the resilient hand of the shooter. Rearward bounce of the pistol of as little as .015" may release and re-apply the pressure of the shooters finger to the trigger, allowing the discon-nector 42 to rise and cause a repeat shot. Since the entire re cocking cycle requires only a few thousandths of a second, the shooter is unable to prevent the occasional occurrence of such a repeat shot. This is a dangerous condition and also an annoying one, since it may cause a target shooter to lose a target-shooting match.

After an extensive study of the problem posed by the above-mentioned difiiculty in firing prior art automatic pistols of the type herein disclosed, I have discovered that the most effective and satisfactory solution of this problem is to inter-pose, between the disconnector 42 and the sear 60, a spring-biased depressor 75 which is pivoted on pin 44 and is provided with a lug 76 aligned to contact the lower end of the sear 60, as shown in Figs. 3 and 4. A U-shaped spring 77, attached at one end to the depressor 75 and at its other end to sear 60, biases the lower end of depressor 75 to the right.

The scar 60 i's rotated to a hammer engaging position by a sear spring (not shown because it is behind the disconnecto'r spring 58) whose lower end is fastened to the grip portion 12 of the frame 10. The hooked end of the depressor springs 77 (Fig. 4) is inserted into a hole 86 in the depressor 75, and spring 77 re-acts against the sear 60 where its other end (having the 90 bend) is inserted into a hole 87 in the sear 60. This arrangement of parts 4 is also clearly shown in Figures 3A, 3B and 3C. The depressor spring 77 is shown in dotted lines where it passes within the sear 60 and is bent at right angles to fit within the sear hole 87. The hooked end is clearly shown inserted in the hole 86 in the depressor 75.

Figs. 3A, B and C show respectively the same relative sequential positions of the elements of my improved lockwork firing mechanism, as are shown in Figs. 2A, B and C, and described hereinabove, for a prior art pistol. In Fig. 3A, the corresponding elements are in the same (normal) positions, as in Fig. 2A. In Fig. 3B, as in Fig. 2B, the elements are in the trigger-back position, in which all the trigger slack is taken up, but the trigger stop 70 is still clear of magazine catch 71. In Fig. 3B, the disconnector 42 has pushed depressor 75 back until the disconnector is touching the lower end of sear 60. Also, in Fig. 3B (as in Fig. 3A), the hammer 34 is held in cocked position by the engagement of sear finger 62 in notch 64, but said finger is about to disengage from said notch and release the hammer.

In Fig. 36, all the elements are in the same positions as in Fig. 20, except that in Fig. 3C the disconnector 42 is held down by the depressor 75, which has snapped ahead and overlies disconnector' lug 59, while the disconnector 42 was held down by slide 16, during the reloading cycle. Since the disconnector 42 is now held down by the depressor 75, instead of by sear 60, it is necessary for the lower end of disconnector 42 to move to the right .035" to .040" before it can rise into the firing position. This means that a trigger jolt movement of .035" to .040" is required to cause unintentional firing of the pistol, and since jolt movement of this magnitude (from the counterrecoiling slide) is very unlikely, the depressor 75 prevents the occurrence of an unwilling repeat shot.

Since (in Fig. 36) the overlap of depressor 75 with disconnector lug 59 is from .035" to .040, as compared with a corresponding overlap of only .010" to .015", between lug 59 and sear 60 in Fig. 2C, the finished dimensions of upper surface of lug 59 and the lower surface of disconnector 42 do not have to be machined to such extremely close tolerances, in the arrangement shown in Fig. 3C, as is required for the prior art arrangement of Fig. 2C. This improvement over the prior art (Fig. 2C) thus materially facilitates and lowers the cost of manufacture of the disconnector 42 and sear 60, which far more than offsets the additional cost of making the depressor 75.

Another novel feature of my invention which constitutes a marked improvement over the prior art pistols resides in the new shape of the end surface of scar finger 62 which contacts the surface of notch 64. Heretofore, the end surface of scar finger 62 was a plane surface whose rear edge travelled in an arc of increasing radius from the center of pivot pin 44, as the sear was rotated in a clockwise movement by the retraction of trigger 36. This caused the hammer to be correspondingly rotated in a counterclockwise direction against the force of the main spring (not shown) and thus increased the pull on the trigger required to fire the pistol. In my improved construction (shown in Fig. 5.), the end surface of sear finger 62 is ground to the shape of a circular arc centered on pin 44 (see Fig. 30), so that there is no movement of hammer 34 when the sear is rotated clockwise by retraction of the trigger 36, and therefore no increase in trigger pull, as in the prior art arrangement mentioned above.

I have found that grinding the end of the sear finger 62 on a constant radius from the center of rotation (pin 44) of the sear, not only solves the long-standing and ditficult problem of obtaining a crisp and light trigger pull, Without hand-fitting the end of the sear finger 62 and hammer notch 64, but also results in the following novel features over the prior art construction: I I (1) The parts can be more easily and rapidly manufactuied.

(2) The sear disengages from the hammer without change in tension.

(3) The amount of engagement with the hammer notch does not affect the trigger pull.

(4) The surface roughness of the hammer notch is not important since only its sharp corner slides across the sear when firing.

(5) Slight relative movement between hammer and sear does not tend to disengage the sear.

(6) Fitting, if required, can be done without touching the sensitive engaging surfaces.

In addition to the improvements just mentioned, it will be noted from the above disclosure that my invention also embodied the following distinguishing features over prior art pistols:

(1) The disconnector 42 and therefore the trigger bar 40 is held away from sear 60 contact after firing. The finger must be released a distance about three times greater than that required to fire before the disconnector 42 can rise into the firing position. In other words, nearly all the trigger slack must be taken up before the pistol can be fired a second time.

(2) The shock of the slide 16 returning home in counterrecoil cannot cause an unintentional repeat shot by jiggling the finger of the shooter in contact with the trigger.

(3) The depressor 75 prevents follow-down when the slide 16 is dropped, while the finger is on or near the trigger 36. The disconnector 42 stays under the depressor 75 until the trigger 36 is released.

(4) The depressor 75 gives slight warning as trigger slack is being taken up, that the disconnector 42 is approaching the sear 60 and the firing position. This is useful in a pistol having a light trigger pull.

(5) In the event that the hammer 34 should followdown when shooting and drop into its half cock notch the trigger 36 is disconnected from the sear 60 and the pistol cannot be fired, even if the half cock notch were damaged. In this condition, the shooter is warned by excessive trigger slack.

While I have shown and described the preferred embodiment of my invention, I desire it to be understood that I do not limit said invention to the details of construction and arrangement disclosed by Way of illustration, since these may be changed and modified by those skilled in the art without departing from the spirit of my invention or exceeding the scope of the appended claims.

I claim:

'1. In an automatic pistol having a reciprocating recoil slide, a firing mechanism comprising: a firing pin, a hammer actuating said pin, a sear engaging and holding said hammer in cocked position, a trigger disengaging said sear from said hammer when said trigger is moved to its fully retracted position, an adjustable stop limiting the retracted movement of said trigger, a disconnector transmitting the movement of said trigger to said sear only when'said trigger nears its fully retracted position and a depressor coacting with said scar and disconnector; means resiliently connecting said sear and depressor, for preventing an accidental repeat shot, caused by the impact of said slide on said trigger when said slide counterrecoils from a previous shot.

2. In an automatic pistol having a reciprocating recoil slide, a firing mechanism comprising: a firing pin, a hammer actuating said pin, a sear engaging and holding said hammer in cocked position, a trigger disengaging said sear from said hammer when said trigger is moved to its fully retracted position, an adjustable stop limiting the retracted movement of said trigger, a disconnector transmitting the movement of said trigger to said sear only when said trigger nears its fully retracted position; and means, coacting with said sear, trigger and disconnector, for preventing an accidental repeat shot, caused by the impact of said slide on said trigger when said slide counterrecoils from a previous shot; said means comprising a depressor, coacting with said sear and disconnector, and holding said disconnector out of its firing position by an overlapping contact therewith of such size to require said trigger to be reset to its forward position, after firing a first shot, before a second shot can be fired.

3. An automatic pistol firing mechanism as in claim 2, wherein said means comprises a depressor which is interposed between said sear and disconnector and holds said disconnector out of engagement with said sear by such a large overlapping contact with said disconnector to prevent the accidental engagement of said disconnector with sear upon a counterrecoil of said slide.

4. An automatic pistol firing mechanism as in claim 2, wherein said sear and depressor are pivotally mounted upon a fixed pivot, and said depressor is spring-biased toward the lower rear end of said sear.

5. An automatic pistol firing mechanism as in claim 2, wherein said depressor is provided with means to prevent said disconnector from prematurely slipping up behind the lower end of said sear.

References Cited in the file of this patent UNITED STATES PATENTS 1,348,733 Pedersen Aug. 3, 1920 1,807,727 Brinkerhofi June 2, 1931 1,840,054 Reising Jan. 5, 1932 2,140,946 Swartz Dec. 20, 1938 2,413,520 Reising Dec. 31, 1946 2,846,925 Norman Aug. 12, 1958 

